1. Field of the Invention
The invention relates to a check disc for confirming playability of a compact disc player, etc.
2. Description of the Prior Art
There is a possibility that various physical defects will occur on a disc such as foreign materials present at the time of disc substrate molding, fingerprints attached during the subsequent manufacturing processes of the disc, etc. and scars occur on the information read-out surface of the compact disc. When such defects occur on the information read-out surface of the disc, a check disc is employed to simulate what the operation state of a disc player is.
Specifically, in a conventional check disc, a usual music signal is recorded, and on its information read-out surface, there are provided simulated defects such as black dots simulating the presence of foreign materials at the time of disc substrate molding, fingerprints consisting of fine dots simulating the presence of fingerprints attached to the information read-out surface of the disc and interruptions made to emit light at random simulating the presence assumption of scars on the information read-out surface of the disc.
With loading of the conventional check disc into a disc player, the simulation of the operation state of the disc player can be carried out for these defects such as foreign materials at the time of disc substrate molding, fingerprints attached onto the information read-out surface of the disc, and scars on the information read-out surface of the disc.
As has been described above, in the conventional check disc, various simulated defects are provided on the information read-out surface of the disc which has recorded a usual music signal. As a result, when the check of the playback state due to defects is done, the state of noises occurring due to the defects is heard differently by the state of reproduced music. In the state where the noise generation state is heard differently by the state of recorded music, correct check can not be made.
Further, in the conventional check disc, there are portions where two kinds of simulated defects of different sizes are in a piece of one track number. Consequently, it is impossible to simulate a playback state when a defect of a predetermined size occurs. As a result, it is desirable to provide one kind of simulated defect present in one piece of one track number. Clearly, if one kind of simulated defect lying in one piece of one track number is provided, the simulation of the playback state can be done immediately only by designating the piece of the track number where the defect of the predetermined size takes place.
Also, the occurrence of other kinds of defects which can not be simulated in the conventional check disc has recently become a problem.
Such defects as fine abrasions on the information read-out surface of the disc that occur when the disc is roughly handled repeatedly and stains that occurred by repeatedly spraying antistatic spray, for example, on the information read-out surface of the disc. Especially in a rental disc such defects are easy to occur, because it is used frequently and its handling is usually rough.